It is well known in the art to use material spreader devices to distribute all types of spreadable material over a selected ground area. Such material spreader devices distribute fertilizers, pesticides, seeds, ice melters, salt, or other materials in particulate or finely divided form over a selected ground area. Generally, material spreaders known in the art can be classified in two general categories: broadcast spreaders and drop spreaders.
Broadcast spreaders generally disperse spreadable material radially outwardly from a hopper holding a quantity of spreadable material. Generally, the spreadable material exits a plurality of large apertures in the bottom of the hopper and drops onto a rotating impeller that rotates in a plane generally parallel to the ground. As the spreadable material interacts with the rotating impeller, the spreadable material is broadcast in an outwardly direction therefrom.
Drop spreaders generally discharge spreadable material downwardly from a hopper holding a quantity of spreadable material onto a selected ground area. Generally, the spreadable material exits a plurality of apertures located in the bottom of the hopper and drops by gravity onto the selected ground area. Drop spreaders generally have a rotatable bar having a radially extending flange mounted just above the apertures at the bottom of the hopper. The rotatable bar assists in breaking up large particles so that they can exit the apertures and further promotes even distribution of the spreadable material over all the apertures within the hopper.
Broadcast spreaders offer several advantages over drop spreaders regarding their use. Broadcast spreaders cast material outwardly over a path wider than the width of the spreader. Therefore, broadcast spreaders can cover a large area with spreadable material relatively quickly as opposed to the narrow paths of drop spreaders. Broadcast spreaders also broadcast spreadable material at a distance above the ground, thereby encountering fewer problems in tall or wet turf or over difficult terrain. Broadcast spreaders push easier, allow faster use, and offer ease of application due to the wide distribution swath and the “feathering” effect at the edges of the distribution pattern. The feathering, or less dense distribution of spreadable material at the edges of the pattern, permits overlap between successive paths thereby permitting a certain amount of error in broadcast application without causing streaking problems. Broadcast spreaders also utilize only a few large metering ports to discharge the spreadable material rather than a series of small ports, thus accommodating larger particle sizes.
However, the several advantages of broadcast spreaders also account for several distinct disadvantages with regard to their use. The most significant disadvantage of broadcast spreaders is the “feathering” effect or lack of control of the distribution pattern. The relatively non-uniform distribution pattern of broadcast spreaders can create numerous application problems. Specifically, the central portion of the distribution pattern has a relatively high particle density and the outer portions or edges of the distribution pattern have a relatively low particle density. In addition, broadcast spreaders are susceptible to pattern changes under windy conditions.
Drop spreaders offer several advantages over broadcast spreaders regarding their use. Drop spreaders are very precise in providing a controlled distribution pattern, a factor of importance in spreading control products such as herbicides. When accurate application of materials is critical, e.g. application of a product near walkways, flower beds, etc., drop spreaders distribute material in a highly uniform pattern over a path essentially the width of the spreader. Further, the uniformity of distribution afforded by drop spreaders does not generally depend on particle size or density because material is dropped by gravity to the ground. Drop spreaders are also generally not effected by wind conditions because they distribute material close to the ground.
However, like broadcast spreaders, the several advantages of drop spreaders also attribute to distinct disadvantages with regard to their use. Because the path width of the applied material is limited to the width of the spreader, drop spreaders are typically slower in covering a ground area of a given size with material as compared to the broadcast spreaders. Also, because the path width is well defined, gaps and/or overlapping occurring between adjacent paths can cause streaking unless the drop spreader is carefully navigated along a path immediately adjacent a previously traversed path. Gaps and overlapping may be undesirable depending on the material being applied. Further, the low ground clearance of the drop spreader may present difficulties when attempting to traverse terrain with high vegetation, ground cover, or abrupt changes in ground contour. Drop spreaders are also sometimes hard to propel, particularly when the container is filled to capacity because the wheels engage the rotating bar within the hopper. Finally, it is sometimes difficult for traditional drop spreaders to consistently provide spreadable material in the lateral direction due to the failure of the rotating bar to push spreadable material laterally within the hopper.
Because both broadcast and drop spreaders have distinct advantages and disadvantages, users are either required to have both types of spreaders or utilize one type of spreader for all applications. Particularly, when applying a spreadable material to a lawn near flower beds, driveways, or sidewalks, a drop spreader more accurately distributes the spreadable material in the concentration desired. Using a broadcast spreader for the same task results in either a low particle density in the area nearest the flower bed, etc. or the misapplication of spreadable material on the flower bed, driveway, or sidewalk. There has been very little effort in the art to provide a spreader having the advantages of both the broadcast and drop spreaders while addressing the disadvantages of both.
U.S. Pat. No. 4,032,074 to Amerine discloses a material spreader having a rotary broadcast type spreader that includes deflection means for deflecting the broadcast material downwardly to form a uniform pattern of controlled configuration. An impeller on the material spreader sends the material outwardly 360 degrees into contact with the interior of the shroud that deflects the material onto the ground in a uniform pattern. However, the '074 material spreader is not constructed to be reconfigured to function as a conventional broadcast type spreader and therefore has limited utility. A need exists for a material spreader that can function as both a broadcast and drop spreader, thereby providing the advantages of both types of spreaders.
U.S. Pat. No. 6,138,927 to Spear et al., hereby incorporated by reference in its entirety into the present application for all material disclosed therein, discloses a dual mode spreader having a spreader disk and a movable elliptical deflection skirt. The deflection skirt is movable between (1) a broadcast position disposed above the path of distribution of the spreadable material by the spreader disk enabling the spreadable material to be broadcast onto a ground area, and (2) a drop position disposed within the path of distribution of the spreadable material by the spreader disk to deflect the spreadable material to move downwardly onto a ground area from the periphery thereof. A disadvantage with the '927 dual mode spreader construction is that the device utilizes the spreader disk in both the broadcast mode and the drop mode. Any disablement of the spreader disc or the broadcasting means of the device will also disable the use of the spreader in the drop mode. Further, the drop mode is not constructed to accurately distribute spreadable material over a specifically defined area (e.g. adjacent walkways, flowerbeds, or driveways. Because the spreader disc launches spreadable material into contact with the elliptical skirt, and the spreadable material deflects off the skirt interior, spreadable material very often falls outside the desired path of the spreader and contaminates adjacent areas.
Therefore, there is a need in the art for a device that can utilize the advantages of both a broadcast spreader and drop spreader and overcome the disadvantages of the prior art devices.